Method of impregnating fiber insulation board



Feb. 22, 1955 c. P. MANNHElM 2,702,761

METHOD OF IMPREGNATING FIBER INSULATION BOARD Filed July 12, 1949 UnitedStates Patent 9 METHOD OF IIVIPREGNATING FIBER INSULATIGN BOARD Carl P.Mannheim, Livingston, N. L, assignor to The Celotex Corporation,Chicago, 111., a corporation of Delaware Application July 12, 1949,Serial No. 104,209

4 Claims. (Cl. 117-43) This invention relates to the improvement in thattype of roofing and siding products which are manufactured of a core offiber insulation board provided on a face with a weather-resistingsurfacing. Such weather-resisting surfacings usually comprise granulesof the general type of roofing granules adhered by asphalt, andgenerally patterned as with mortar joint simulation to form a brick orstone pattern, or the like.

In the manufacture of these products, various additional features areincorporated by various manufacturers. In general, the units arerectangular, about 16 inches wide and 4 feet long, but, as mentioned,this varies with the difierent manufacturers. Usually, at least the longedges of the units are shiplapped. Some manufacturers shiplap both thelong and short edges. Usually the blanks or cores of fiber insulationboard are treated to impart rigidity and weather resistance. Thisgenerally comprises a surface saturation or impregnation with an asphaltor other bituminous substance. It is the general practice that thetreatment of the cores to impart rigidity and weather resistance, insome form, is a limited saturation or impregnation with asphalt appliedin different ways by different manufacturers, it being understood thatthe most common method is that of merely dipping or passing the coreelement through a heated asphalt bath so that all the surfaces aresaturated or impregnated to a limited extent with asphalt.

Ordinarily such coated blanks then have a further coating of asphaltapplied to one of the broad surfaces, and the weather-resistant granularmaterial is then suitably applied to this coating and embedded thereinto be adhered to the face of the unit. The units are then processed toprovide such mortar simulating lines, or the like, as are desired in thefinished product.

In the coating of the insulating cores with asphalt, as above referredto, it results that the surface saturation or impregnation of the fiberboard core is more or less unlform, although it has been noted that ingeneral there is slightly greater penetration of the asphalt into theedges of the core than into the faces, which results from the basicstructure of fiber insulation boards whereby the porosity is greater inthe direction inwardly from the edges than inwardly from the faces.

In the use of these insulating siding products as manufactured ingeneral, as above described, it has been found that for best results,for various reasons the edge portions should be substantially completelyimpregnated with the protective asphalt. The face of the unit isprotected not only by the original coating of the blank, but it isfurther protected by the additional coating of asphalt material in whichthe granules are embedded. The edges of the units do not have theadditional protection of the granular adhering coating, and according topast procedures there has been no treatment whereby the edges of thecores might be sufliciently impregnated without excessively impregnatingthe faces of the cores.

It is the particular object of this invention to provide a manufacturingprocedure whereby, in the regular production of insulating siding, theedge portions of the cores may be suitably and sufficiently impregnatedto impart the desired additional strength and weather-resistancerequired without undue impregnation or saturation of the cores inwardlyfrom their broad faces. That is, it is a procedure for dilferentiallysaturating the core but in a single saturating operation. It has beendetermined that by pre-heating a limited portion of a piece of fiberinsulating board it is possible to differentially saturate the board dueto the fact that the pre-heated portion will absorb asphalt more readilythan does the unheated portion or portion which is relatively cooler.

Particularly an object of this invention is the provision of a processfor obtaining differential impregnation of fiber insulation board with athermoplastic saturant, and wherein through the heating of selectedportions of such board, where it is desired that the impregnation shallbe more complete, to bring about differential absorption of moltenthermoplastic saturant whereby a predetermined selected portion of thesheet of fiber insulation board is more completely impregnated than isother portions of such board.

The specific steps of procedure provided for achieving the objects or"the invention involve the pre-heating of limited predetermined portionsof a sheet of fiber insulating board, followed by immersion of suchprepared sheet of board in a bath of the molten thermoplastic saturantwhile the pre-heated portions of the board are still heated with respectto the rest of the sheet, and finally, subjection of the sheet to asurface wiping or squeegeeing operation and suitable cooling to solidifythe thermoplastic saturant.

Herein, in order to avoid confusion with respect to the use of theterms, attention is directed to the fact that the words impregnation andsaturation are in general relatively loosely used terms, and thereforeit is desired to point out specifically the sense in which such areherein used. For the purposes hereof, the term impregnate orimpregnation is used in the sense of physical incorporation in thestructure, that is, herein the asphalt flows into the interiorinterstices between the fibers of a piece of fiber insulation board whensuch is placed in a bath of melted asphalt. The term saturate orsaturation comprises a complete impregnation, that is, such is used inthe sense that when a piece of board is impregnated, as above, toincorporate the maximum of the asphalt to fill the interstices betweenthe fibers of the board structure, such is then considered saturatedboard. As used herein, a 75% saturation exists where the board has beenimpregnated with 75% of the amount of saturant required to completelyfill the fiber interstices or completely saturate the board. It is to beunderstood, of course, that absolute saturation is substantiallyimpossible, but for the purposes hereof a sheet is considered to besaturated when it has absorbed all of the saturant which can be taken upby the sheet in ordinary manufacturing procedures.

In the accompanying drawings, Figure 1 is a perspective of a unit;Figure 2 is an edge elevation of the end faces of a fiber insulatingboard blank; and

Figure 3 is an elevation of the side or long edges of a fiber insulatingboard blank.

In the drawings the more heavily shaded portions indicate those portionswhich have been impregnated with the saturant in accordance in theprocedure of the processes hereof.

In the drawings the fiber insulating board blank is identified bynumeral 10. This blank is shown as a shiplapped board on its long edgesand short edges, the shiplapped tongues of the long edges beingidentified by numerals 11 and on the short edges by the numerals 12. Theimpregnated face portions are identified as 15 and impregnated edgeportions as 16.

To accomplish the objects of the invention hereof, the blank edges aresubjected to heat to raise the temperature of the edges above thetemperature of the remainder of the sheet. It must be understood thatthe objects hereof will not be achieved if the entire fiber board coresheet is heated, since if the entire core is heated the degree ofsaturation of the broad faces will be increased to with the facesprotected, from appreciable heating by the use of heat insulationinterposed for such purpose. This object may be achieved by applying toeach broad face of the fiber board core a sheet of fiber insulationboarder the like 20' which, as is evident, dimensionally should beslightly less than the length'of and width of the core 10, less twicethe depth of the respective rabbets of the shiplap. Assuming the widthof 'the core sheet in Figure 1 to be 16 inches and the long edges of therabbets as having a depth of three-fourths inch, then the width of theinsulating sheet 29' will be about 13 to 13 /2 inches.

When an assembly comprising a core sheet with an insulating sheet suchas 29, applied to each of the broad faces thereof, is placed in an ovenat. an elevated temperature, it will be readily understood that theperiphery or edge portions of the core sheet will be heated, whereas,due to the protection aiforded by insulating sheet 20, the body portionof the core sheet 10 will be substantially unaffected.

According to the specific procedure which has been worked out, the edgesof the core are raised to a temperature of about 425 to 450 F. Thistemperature is not critical, but the edge temperature must be raisedsulficiently to obtain the desired penetration but should not be raisedto such temperature as will cause charring of the fiber, in connectionwith which most fiber boards will char at a temperature of around 500.

The steps involved in the processing hereof comprise the selectiveheating of the edges of a core 10 by the procedure just above described,whereupon the core, with its edge portions at substantially the elevatedtemperature set out, is passed into a bath of molten thermoplasticsaturant, which conveniently is a suitable asphalt; for example, apressure still tar having a melting point (ball and ring) of about 137to 142 F., penetration at about 90' to 115 F. and a flash point(Cleveland open cup) of about 480 F., which asphalt bath, for thepurposes he'geoi" should be carried at a temperature of around 40 Thefiber board core with the edge portions preheated, as above described,when submerged in an asphalt bath such as above described, for anyreasonable period, will show a definite differential of impregnation asbetween the preheated edge portions and the the portion interior thereofwhich was not preheated. For the usual fiber insulating board core, itwill be found that an immersion for about seconds will provide animpregnation at the preheated edge portions amounting to approximately80% saturation, a quarter inch tongue portion being completelyimpregnated. That is, with the saturant extending entirely through thetongue portion, whereas, on the other hand, the impregnation of therelatively cooler faces, interiorly of the edge portions, will extendonly to a depth of about .07 inch inwardly from the surface. Theforegoing is with reference to a core board approximately one-half inchin thickness, so that the tongue of the shiplap is approximatelyone-quarter inch thick, so that obviously, since in accordance with theprocedure set out, the tongue portion becomes impregnated throughout,the saturant penetrates into the preheated portion to a depth of atleast one-eighth inch, or 0.125 inch. It has been pointed out that theface portions of the core 1%), which are protected from heating by theapplication of the insulating sheets 2%), are penetrated to a depth ofonly approximately 0.07 inch, so that the preheating of the edgeportions causes the saturant to penetrate to about twice the depthcompared to the parts of the sheet which are not heated.

After the core 10 has been submerged in the molten thermoplastic, it isthen removed and passed through wiping rolls, or squeezed to remove anyexcess saturant on the surfaces, and then the sheet may either coolnaturally or may be subjected to forced cooling.

The processing of the fiber board core for insulating siding, roofing orthe like, in accordance with the foregoing, accomplishes a plurality ofobjectives. By having a high degree of saturation of the edges, theedges of the sheet are stiffened, and they are protected againstpenetration of water into the body of the sheet from the edges. Wherethe edge portions are 80% saturated, it results that actually the outerportions are'substantially 100% saturated, with the degree of saturationdecreasing slightly inwardly away from the extremities of the sheet. Itis, of course, preferable to retain as high a degree of insulation aspossible so that the product serves two functions, one, as an exteriorcovering for a building or the like, and the other as insulation againstheat transmission. Since the face of the finished product, as previouslydescribed, is protected by the application of a coating of asphalt inwhich the surfacing material is embedded, the holding down of thepenetration of the saturant to a depth of approximately 0207, as'abovereferred to, provides ample weather protection in conjunction with theadditional asphalt surface coating which is applied. This limitedpenetration of the saturant into the face portions ofthe' core obviouslyleave the interior portions of the core to function as heat insulation.

The process as described herein shows a very considerable saving ofasphalt as compared with ordinary impregnation procedure, as has beenheretofore practiced, and which comprised merely the submerging of thecore in the molten thermoplastic, whereby substantially uniformpenertation of all parts of the core resulted, and according to whicheither the faces of the cores were oversaturated or the edge portionsunder saturated. 'If the conditions of saturation were such thatthequarter-inch tongues would be completely impregnated to something likesaturation, then the body portion would be impregnated to substantiallythe same degree, requiring a large amount of saturant and largelydestroying the insulating value of the interior body portion of the corepiece.

By the practice of the invention hereof, it is possible to obtain adifferential degree of impregnation, according to which the'heated edgeportions are penetrated by the saturant to about twice the depth of thepenetration of the saturant into the protected and consequently unheatedinteri'or portion of the core. This process obviously results inachieving the desired substantially complete saturation of the edgeportions of the core, with the consequent stifiening and protectionagainst the penetration of water, and, at the same time, results inquite a considerable saving of the thermoplastic saturant used, sinceover the large areas of the face surfaces of the sheet the penetrationis restricted to a relatively shallow depth with the consequent savingas compared with the penetration similar to the penetration of thesaturant into the edge portions, which would consume nearly twice theamount of saturant as used in the practice of the inventions hereof.

While the foregoing description has been substantially limited to thedescription of the impregnation of the fiber insulation board withasphalt, it is to be understood that the principles described are merelyrepresentative, and are applicable generally. For example, the coresheet, or sheet which is impregnated, 'may be a board-form sheetcomposed of various fibers-wood fibers, bagasse fibers, glass fibers,asbestos fibers and the like. Also, the sheet may be composed ofelements other than fibers, the process being generally applicable toany sheet having a structure incorporating connected porosity orinterstices between the elements comprising such sheet. Also othersaturants may be used instead of asphalt, as, for example, variousasphaltic type saturants, thermoplastic resins, rosin, solid waxes, andother thermoplastic solids which will be known to those skilled in theart. Finally, while the description deals in particular with the greaterdegree of saturation of the edge portions of the core, achieved throughthe heating of the edge portions, the teachings hereof may bealternatively applied to the reverse situation. That is, selected innerportions of the core may be more highly saturated than the edge portionsthrough the heating of selected inner portions of the sheet as comparedwith the other portions and/or edge portions.

The inventions hereof having been described in full detail, I claim:

1'. The process for impregnating a porous sheet material to differentdegrees of saturation in predetermined different parts thereof andcomprising the steps; apply- I ing heat to limited pro-selected portionsof the sheet without appreciably raising the temperature of theremainder of the sheet, and whereby the temperature of such preselectedportions of the sheet is raised relative the 'remainder of the sheet,then with the sheet dilferentially so heated, immersing the sheet in hotfluid thermoplastic saturant and. removing the sheet from the hot fluidthermoplastic saturant upon the lapse of the period of timepredetermined to result in the depth of saturation desired.

2. The process for impregnating a fiber insulation board tosubstantially saturate the edge portions thereof to a greater degree ofsaturation than that of the saturation of the field of the facesurfaces, and comprising the steps of heating the edge portions of thesheet of fiber board to a temperature appreciably above the temperatureof the remainder of the body of the fiber insulating board, andimmersing the fiber insulating board with its edge portions so heatedrelative the remainder of the body of such sheet in hot fluidthermoplastic saturant for a limited predetermined time sufficient toobtain a predetermined limited impregnation of the field portions of thefaces of such sheet, and whereby due to the relative higher temperatureof edge portions of such sheet, a deeper and more complete impregnationof such heated edge portions is obtained.

3. The method of obtaining differential absorption in different portionsof a structural board having inter-connected porosity throughout thebody thereof and comprising the steps of applying protective insulatingbodies against pre-selected portions of surfaces of such sheet ofmaterial, subjecting such assemblage of structural board and heatinsulating bodies to heat, for a predetermined time and at a.predetermined temperature, to heat those portions of the structuralboard not protected by the heat insulating material to a temperaturewhich is higher than the temperature of the portions thereof protectedby the heat insulating material, and then immersing the sodiflerentially heated structural board in hot fluid thermoplasticsaturant for a limited predetermined time whereby impregnation of asheet is of its surfaces only without impregnation throughout the sheet,removing the board from the saturant bath and allowing the impregfromthe heated body of thermoplastic saturant upon expiration of the periodof time requisite for obtaining a desired limited impregnation of thefluid thermoplastic saturant measured inwardly from the exteriorsurfaces thereof.

References Cited in the file of this patent UNITED STATES PATENTS1,552,421 Cumfer Sept. 8, 1925 1,776,586 Heppes Sept. 23, 1930 1,890,017MacDonald Dec. 6, 1932 2,512,371 OReilly June 20, 1950 FOREIGN PATENTS349,654 Great Britain Mar. 6, 1922

1. THE PROCESS FOR IMPREGNATING A POROUS SHEET MATERIAL TO DIFFERENTDEGREES OF SATURATION IN PREDETERMINED DIFFERENT PARTS THEREOF ANDCOMPRISING THE STEPS; APPLYING HEAT TO LIMITED PRE-SELECTED PORTIONS OFTHE SHEET WITHOUT APPRECIABLY RAISING THE TEMPERATURE OF THE REMAINDEROF THE SHEET, AND WHEREBY THE TEMPERATURE OF SUCH PRESELECTED PORTIONSOF THE SHEET IS RAISED RELATIVE THE REMAINDER OF THE SHEET THEN WITH THESHEET DIFFERENTIALLY SO HEATED, IMMERSING THE SHEET IN HOT FLUIDTHERMOPLASTIC SATURANT AND REMOVING THE SHEET FROM THE HOT FLUID